in RELATIONSHIP TO REPTILES 39 



Quaternary. Some of these were of gigantic size, 

 larger even than the Ostrich. Like Archaeoptcryx, 

 they had teeth. In Hesperornis, to take one example, 

 these are very reptilian, in the way they are set in a 

 long hollow in the jaw, in the absence of root and of 

 cement on the neck of the tooth, in the way they 

 were changed, a young tooth being formed on the 

 inner side of the base of the old one. But by this 

 time birds had lost their great length of tail. 



Here it will be instructive to mention the discovery 

 in existing birds of what were supposed to be the 

 rudiments of teeth. If you take the beak of a Parrot 

 and macerate it well, you can separate the horny beak 

 from the bone beneath. The horn is only a form of 

 epidermis and, therefore, we should expect to find 

 skin underneath. Skin is found and on it papilla:, 

 small pimple-like elevations, similar to those found 

 beneath a horse's hoof. They nourish the growing 

 and quickly wasting beak. And these were the 

 " rudimentary teeth " which so much interested the 

 zoological world. But here, as often, a false theory by 

 stimulating investigation has led the way to the true 

 one. 1 



There are some very remarkable points of agreement 

 between crocodiles and birds. The ordinary reptile 

 has only three chambers to his heart. The crocodile's 

 heart, though still a very imperfect organ, has four 

 see p. 284). He has a gizzard and habitually 

 swallows stones to aid in digestion. His lungs are 

 far more elaborate structures than those of a lizard. 



1 See Bronn's Thier- Reich, vol. " Aves," p. 501. 



